An example of battery packs in which battery modules are installed in a vertically extending member is a rechargeable battery device disclosed in Patent Document 1. The rechargeable battery device of Patent Document 1 includes a plurality of layered cell assemblies. Each layered cell assembly includes a floor plate, a back plate extending vertically from the floor plate, and a base plate fixed on the floor plate. A battery module is placed on the base plate and contacts the back plate. Side plates are vertically arranged on the base plate to sandwich the battery module. A packing is arranged on the battery module, and another base plate is arranged on the packing. Another battery module is then placed on the base plate. In this way, the battery modules are layered.